Answer:
0 %
Explanation:
As we know 10.81 is the average atomic mass of boron which can not be contained by a single boron atom. Therefore, when isolated, a single boron atom will weight either 10 amu for ¹⁰B and 11 amu for ¹¹B respectively.
The average atomic mass is calculated as;
Atomic Mass of ¹⁰B = 10
Atomic Mass of ¹¹B = 11
Natural Abundance of ¹⁰B = 20 %
Natural Abundance of ¹¹B = 80 %
So,
Average Atomic Mass = (10 × 0.2) + (11 × 0.8)
Average Atomic Mass = 2 + 8.8
Average Atomic Mass = 10.8